Since the advent of indexable, wafer-like cutting inserts, sometimes referred to as throwaway inserts, there have been numerous disclosures of the use of sinusoidal or serrated edges on these inserts. This results in smaller chips and greatly reduced chip load. The cutters are arranged in a multiple blade rotating head so that they are staggered to insure a full cut of the material surface being removed, but each projection takes just a "nibble" at the workpiece.
Examples of this type of insert are found in the United States patent to Owens, U.S. Pat. No. 3,636,602, dated Jan. 25, 1972, and to Malinchak, U.S. Pat. No. 3,875,631, dated Apr. 8, 1975. These cutters are particularly useful in roughing cuts. According to the present invention, a hard wear resistant cutting insert is provided which has faces on opposite sides facing in opposite directions and a peripheral surface extending between the faces. When viewed perpendicular to a face, the insert is polygonal, preferably, rectangular, and each edge of the insert between the respective corners is notched or grooved so that, when that particular edge of the insert engages a surface being worked, the regions of the edge between the notches or grooves will remove material from the workpiece while material will not be removed from the workpiece in the region of the notches or grooves.
When two such inserts are arranged in tandem with one following the other in spaced relation, the second insert is arranged to remove those portions of the workpiece left by the preceding insert, and with this in mind, the several edges of the inserts have at least two different numbers of grooves formed therein so that a pair of inserts can be arranged in different indexed positions and the following insert will remove what is left on the workpiece by the preceding insert.
In this manner, the holders for the inserts can be arranged to locate the inserts in a precise position by means of abutments and the insert clamped in the position and the inserts will be aligned to cooperate in the aforementioned manner.
The present invention contemplates edges of inserts with different numbers of grooves or serrations in either opposed or adjacent edges so that when arranged seriatim, a full cut will be made. For example, if two opposed edges have four indentations to provide five (including the corners) cutting projections, then the other two opposed edges (of a square insert) can have three indentations to provide four cutting projections. These projections and indentations are spaced so the combined nine cutting projections in superimposed relation provide a full sweep of the workpiece.
Thus, if there are "n" indentations or notches on one edge of an insert, there can be "n+m" notches on an adjacent edge to provide a full sweep of the work.
This arrangement greatly simplifies the setting up of a milling cutter or the like in which the inserts are provided with grooves in the edges to distribute the cutting load between the inserts.
Other objects and features of the invention will be apparent in the following description and claims in which the principles of the invention are set forth together with details to enable a person skilled in the art to practice the invention, all in connection with the best mode presently contemplated for the invention.